Detect Obfuscated PowerShell Command Invocation via Stdin on Windows

Flags PowerShell-like command-line patterns indicating obfuscated execution using stdin or input substitution.

FreeReviewedSigma · High · v2

Product: windows
Category: process_creation
Author: Nikita Nazarov, oscd.community (SigmaHQ), DRL 1.1
Published: 2020-10-12
Updated: 2026-07-31

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1059.001PowerShell
Persistence
Priv Esc
Defense Evasion
- T1027Obfuscated Files or Information
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags process creation events where the command line matches patterns indicative of PowerShell obfuscation involving stdin-style input handling and chained commands. Attackers use obfuscation to hinder analysis and increase the likelihood of successful execution while maintaining stealth. The detection relies on Windows process creation telemetry, specifically the PowerShell command line content matching the configured regular expression.

Reporting behind it

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Detect Obfuscated PowerShell Command Invocation via Stdin on Windows

Pivot detection · T1027 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

powershell-stdin-obfuscation-execution-from-command-line-9c14c9fa

title: Detect Obfuscated PowerShell Command Invocation via Stdin on Windows
id: 929d2e2b-2f52-49cc-ba21-bc2426bd4a6b
status: test
description: This rule flags process creation events where the command line matches patterns indicative of PowerShell obfuscation involving stdin-style input handling and chained commands. Attackers use obfuscation to hinder analysis and increase the likelihood of successful execution while maintaining stealth. The detection relies on Windows process creation telemetry, specifically the PowerShell command line content matching the configured regular expression.
references:
  - https://github.com/SigmaHQ/sigma/issues/1009
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_hktl_invoke_obfuscation_via_stdin.yml
author: Nikita Nazarov, oscd.community, Huntrule Team
date: 2020-10-12
modified: 2026-03-16
tags:
  - attack.stealth
  - attack.t1027
  - attack.execution
  - attack.t1059.001
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    CommandLine|re: (?i)(?:set).*&&\s?set.*(?:environment|invoke|\$\{?input).*&&.*"
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 9c14c9fa-1a63-4a64-8e57-d19280559490
    type: derived

Convert

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